Detectives began investigating the crime around 6:30 a.m. Friday, after a person was discovered dead on the second level of luxury apartment building 9 on Canal.

The coroner later identified the victim as Carina Rodriguez, 22, and determined she died of a stab wound. Her family told WXIN she had just moved to Indianapolis from Texas to start a new life with her son and go back to school to get her associate’s degree in the medical field.

Police arrested Weir in the parking lot of a Best Buy store in Avon last Friday afternoon. Officials say a lifelong acquaintance recognized Weir from surveillance video recorded in the lobby of the apartment complex.

Carina Rodriguez

One detective calls Weir “a predator,” and says he believes the homeless man from Hendricks County was prowling early Friday morning for a target of opportunity when he spotted 22-year-old Carina Rodriquez working out in the fitness room.

According to court documents, Rodriguez was alone in the gym at 2:44 a.m. when the suspect approached the locked gym door. She let him in and he proceeded to drink from the water fountain. He told authorities he was angry and tried to calm himself down by drinking water.

He then allegedly struck her with a knife at 2:45 a.m.

After a struggle that left Rodriguez on the floor of the gym, police say Weir ran out. After he left, Rodriguez stood up, staggered towards her bag, pulled out an iPad and attempted to use it, according to court documents, before she fell to the ground unresponsive at 2:49 a.m.

Investigators said they found Weir's Pontiac Grand Prix in a handicap parking space near the complex's main entrance. Inside, officers found a Gerber brand fixed-blade knife with possible blood on the handle and blade, a hooded jacket with a Batman symbol, a pair of jeans and work boots, all with possible blood, according to police.

A cigarette pack and key fob were also found.

After police released surveillance video to the media, several people called and claimed Weir was the suspect. One person who knows him called him after speaking with police. Weir allegedly told him he blacked out and couldn't remember anything.

That person convinced Weir to meet him in the parking lot where officers took him into custody, according to police.

When detectives interviewed Weir, court documents show he initially told them he didn't really remember anything. He said he'd been in the building before because he had a friend who lived there. He also told police he still had a key fob for the building.

He said he usually kept a knife in his car, and that he used it for work. He then recalled the victim letting him into the gym.

"I think I knocked on it, and she let me in, and I told her 'thank you,'" he said, according to court documents. "I had a knife in my hand. I remember hitting her and then I ran."

Police then arrested Weir on a charge of murder.

In 2014, Weir was found not guilty of rape in Hendricks County and is reportedly known to Avon Police.

Detectives continue to investigate Weir’s history and activities the night of the killing.

A 9 on Canal spokesperson said the exterior door is not required to be locked, as it provides access to another gym and a burger restaurant. All doors in the building that were required to be locked were, including access to the residences and the door to the gym where Rodriguez was found dead.

Even if Weir obtained the fob from a former resident, the spokesperson said it should have been deactivated if it wasn't collected by management. The spokesperson said if anything could have been done to prevent the murder, they would have done it.

One woman told WXIN that Weir contacted her on social media hours before the murder in anticipation of a sexual encounter.

A source confirms Weir was crying and confessional after his arrest. His initial hearing in court is set for Tuesday at 1 p.m.